1. Field of the Invention
The present invention relates to a radio communication apparatus and method which utilize a so-called software radio technique and are compatible with a plurality of communication systems or applications due to changing programs.
2. Description of the Related Art
Software radio devices have been proposed as one of the means for realizing a multi-mode terminal. In such devices, at least part of the signal processing necessary for signal transmission or reception is executed by software, using a programmable device such as a digital signal processor (DSP). The basic idea of software radio devices is known from, for example, Jpn. Pat. Appln. KOKOAI Publication No. 9-331579. However, how to realize such devices under various conditions has not been sufficiently disclosed.
The unit in a software radio device that deals with a baseband signal, i.e., a modem, processes a large amount of data, and is required to execute high-level processing such as protocol stack, system control processing, and sometimes application data processing. Therefore, the modem is subject to a design change each time the standards for the communication system are changed. The aforementioned programmable device can cope flexibly with such a design change through a change in the software. However, the capability of a programmable device such as a DSP may be insufficient for high-speed processing of broadband radio communication signals.
To make a software radio device handle a new communication system, or to add a new application service function, it is necessary to prepare the necessary free resources. Resources management is also necessary for optimally sharing one resource between communication systems or services.
As a general design concept for radio communication apparatuses, resources are assigned to a plurality of signal processes at a predetermined ratio. If this concept is applied to software radio devices, the rate of use of each resource is significantly reduced since the radio communication apparatuses must deal with a plurality of communication systems or application services.